The present invention relates to an IC card which can set at least one security level for every memory area and, more particularly, to an IC card which can access a desired area in a memory after confirming that a predetermined secret identification number had been input.
IC cards are also called smart cards and not only flat-shaped cards but also key-shaped or stick-like cards, and the like exist. Therefore, it is assumed that IC cards according to the present invention include all of those cards.
The IC card in which a desired memory section is accessed after confirming that a predetermined secret identification number had been input has been disclosed in, for example, U.S. Pat. No. 4,211,919. According to this patent, data can be written and read out from the outside into a data memory area as a whole, and this data memory area can be accessed for reading and writing data only when a predetermined secret identification number is input, and what is called a security level of the memory area is unified.
In accordance with the kinds and contents of data, there is the case where the data needs to be classified into the data at several security levels such as: data having no secrecy such as data of the content informing commercial messages of the card issuer or data like card use rules such as "this card cannot be lent to others" and the like; data having an extremely high secrecy such as balance of account, clinical history, or the like; data concerned with the drawing of cash of the savings which requires not only the secrecy but also the safety; data which requires the secret identification number for every business unit as in what is called a composite IC card in which data of a plurality of business units among banks, credit companies, department stores, securities companies, hospitals, and the like is stored in a single IC card; and the like. Particularly, in association with a variety of uses of IC cards and the highly advanced use styles of IC cards, it is required to provide various kinds of security levels in use of the same card.